Oscillator



May-12, 1942. P. c. C'EARDINERI 2,282,861 A OSCILLATOR Filed Oct. 2,1940 FigL (125 TUNER AND \l 24 mpunm 3;; g2? 2 f /3 FUN ANL AMP IERInventor: Paul C. Gardiner,

His Attorney.

Patented May 12, 1942 OSCILLATOR Paul C. Gardiner, Scotia, N. Y.,assignor to General Electric Company, a corporation of New YorkApplication October 2', 1940, Serial No. 359,364

3 Claims.

My invention relates to oscillators and'more particularly to oscillatorsarranged to generate ultra-high frequency waves.

The utilization of ultra-high frequency waves ate at ultra-highfrequencies and arranged to transmit a wave over a metallic circuit to aload device at high efficiency, even though the load device bepositioned at some distance from the oscillator.

A further object of my invention is to provide an oscillator fortransmitting such waves over a conductor in which the conductorcooperates with other portions of the oscillator. to generateoscillations and at the same time transmits the oscillations from theoscillator in an efficient manner. 1

The features of my invention which I believe to be novel are set forthwith particularity in the appended claims. My invention, itself,however, both as to its organization and method of operation, togetherwith further objects and advantages thereof may best be understood byreference to the following description taken in connection with theaccompanying drawing in which Fig. 1 illustrates an embodiment of myinvention; and Fig. 2 illustrates a modification thereof.

In Fig. 1, I have illustrated my invention in a system in whichultra-high frequency radio waves are received through an antenna 10 andtransmitted through a tuner and amplifier H to an electron dischargedevice 12 to be heterodyned therein with waves generated by anoscillating discharge device l3. The output of the tuner and amplifier Il is impressed across a tuned circuit 44, an intermediate point of whichis connected through a coil l5 and a condenser H3 in series to thefirst, or control, electrode I! of the device [2. The control electrode[1 is connected through a resistance IE to ground and the cathode I 9 ofthe device '12 is connected through a biasing resistance 26 to ground.Space current flowing through the device I2 and through the resistance20 produces a bias potential between the cathode l9 and the controlelectrode I1. The

resistance is shunted by a condenser 2| to maintain the cathode l9 atground potential for radio frequency current. The anode 22 of the deviceI2 is connected to a suitable tuned output circuit 23.

The discharge device 12 is operated on a nonlinear portion of itscharacteristics, so that Waves from the antenna 10 impressed on thecontrol electrode I! are heterodyned with Waves which may convenientlybe impressed on the coil I5. The oscillating discharge device l3produces such waves to be transferred to the coil l5 for heterodyneaction with the wave from the antenna). A source 25 of operatingpotential for the oscillating device 13 is-connected between theanode 24thereof and ground. The control electrode 26 of the device 13 isconnected through a resistance 21 to ground and coupled through acondenser 28 to one terminal of atuned circuit 29, whose other end isgrounded. The control electrode 26 is also coupled through a condenser30 to the cathode 3| of the device l3. The cathode 3| is conductivelyconnected to ground through a conductor 32 and a coil 33, the latter ofwhich is positioned near the converter device l2. The coils l5 and 33'are placed in inductive relationship, so that the wave generated by thedevice I3, as well as thewave from the antenna [0 transmitted throughthe tuned circuit I4, is impressed on the control grid l1.

All of. the apparatus illustrated is mounted on a common chassis, whichis referred to as ground.

Becausethe waves transmitted through the circuits of this apparatus areof extremely high frequencies, such, for example, as a frequency ofmegacycles, the physical dimensions of the various circuit elementsmake'it impossible to arrange connecting conductors. sufficiently shortto transmit waves .efilciently from the device |3 to the device l2. In aparticular super heterodyne receiver the conductor 32 was made about 8inches long in order to reach from the cathode 3| of device I3 to thecoil 33 nearthe device 12. Unless special precautions are takendifficulty is likely to be encountered in transmitting required voltageover such a conductor.

In accordance with my present invention such difficulty is overcome in aparticularly efiicacious and satisfactory manner. The conductor 32,which may, for example, be about 8 inches long or of any other length asrequired in suchapparatus, is connected between the cathode 3t and thecoil 33 to provide a path for space current I from the cathode 3|through the coil 33 to the chassis. The conductor 32 was also arranged v3| is maintained at an alternating potential in; termediate thepotentials of the terminals of the tuned circuit 29 by the voltagedividing actionof two capacities. capacity 30 connected betweenithecathode 3| and the control electrode 26, and the other is the capacity34 between conductor 32 and the chassis, the magnitude of which isadjusted by One of these capacities is the relationship, so that a wavegenerated in the circuit 29 varies the voltage of the cathode l9. Thecontrol electrode ll of device I2 is coupled through the condenser |6directly to an intermediate point of the tuned circuit l4.

A wave from the antenna I0 is transmitted through the tuned circuit I4and impressed between the control electrode I1 and ground. A wave fromthe resonant circuit 29 is impressed through the coils 4|] and 4|between the cathode l9 and ground. These two waves produce heterodyneaction in the device l2 and the circuit 23 of the anode 22 may thereforebe tuned to a wave -whose frequency is the sum or the difference of ;thefrequencies of these two waves.

The oscillator including the discharge device l3 and the resonantcircuit 29 as illustrated in Fig. 2 is connected differently from Fig.l. The

proper positioning of the conductor 32 with respect to the chassis.Since one terminal of tuned circuit 29 is connected to they chassis thisca pacity 34 exists between that terminal and cathode 3|.

The impedance of conductor 32, measured between the cathode 3| and thechassis, is substantial at the operating frequency of the oscillator.This impedance has a conductive component including the resistance andthe inductance of conductor 32. It also has a, substantial capacitivecomponent represented by the capacity 34, which is of proper impedanceto provide, in conjunction with condenser 36, the voltage dividingaction just described. The conductor 32 does not produce a short circuitacross the capacity 34 because it is sufficiently long so a to presentsubstantial impedance between the cathode 3| and the chassis. Thecathode 3| is thus not maintained at ground potential and the conductor32 is an operating portion of the oscillator.

Since the coil 33 has substantial impedance relative to the impedance ofthe conductor 32, and since the reactance of the condenser 34 at theresonant frequencyof the circuit 29 i substantial, energy is readilytransferred from the resonant circuit 29 through the conductor 32 to thetransformer including coils l5 and 33.

The conductor 32 in addition acts as a choke coil to supply operatingpotential to the cathode 3|. This may be seen by tracing the circuitthrough which space current flows, as follows: Current from the sourceflows through the anode 24, cathode 3|, conductor 32, coil 33, ground,and back to the source 25. It should be noted that the path throughwhich this space current passes includes the conductor 32 and ground,and that the ends of the path lie adjacent each other near the cathode3| and the grounded terminal of tuned circuit 29 to provide the capacity34 therebetween.

- For convenience of operation means are provided to vary thefrequencyto which each of the tuned circuits 4 and 29 is adjusted, and thesetuning means are arranged to be operated in unison by a singlemechanical control, as indicated by dotted lines.

,Fig. 2 illustrates a different embodiment of my invention in which manyparts are identical with those illustrated in Fig. l and are given likereference characters. The coils l5 and 33 have been replaced by coils 49and 4|. The conductor 32 is connected through the coil 40 to ground at apoint on the chassis near where the condenser 2| is grounded, and thecathode -|9 is connected through the coil 4| to the resistance 29 andcondenser 2|. The coils 46 and 4| are in inductive anode 24 of thedevice I3 is connected directly to one terminal of the resonant circuit29. The negative terminal of the source 25 of operating potential isgrounded and its positive terminal is connected to the second terminalof the resonant circuit 29. The control electrode 26 is coupled througha condenser 28 to this second terminal of the resonant circuit 29. The'control electrode 26 is also connected through a resistance 21 to thecathode 3|, in order that a bias voltage across the resistance 21 may beproduced for proper operation of the device |3.

The stray capacity 34 between the conductor 32 and ground lies betweenthe cathode 3| and that terminal of the resonant circuit 29 which iscoupled to the control electrode 26. A capacity 35 is connected betweenthe cathode 3| and the anode 24, and forms with the capacity 34 acapacity voltage divider. The operation of the oscillator illustrated inFig. 2 is similar to that of the oscillator illustrated in Fig. 1. Theanode 24 and the control electrode 26 are coupled to opposite terminalsof the resonant circuit 29, and the capacities 34 and 35, operating as acapacitive voltage divider, maintain the alternating potential of thecathode 3| intermediate the potentials of the terminals of the resonant,circuit 29, The conductor 32, as before, has sufficient impedance tomaintain the cathode 3| at an alternating po-' tential with respect toground. This impedance includes the. capacitive component represented bythe capacity 34. Space current for the device I3 flows from the positiveterminal of the source 25 through the resonant circuit 29, anode 24,cathode 3|, conductor 32, coil 40, and ground back to the negativeterminal of the source 25.

The above described inter-connections of the oscillator including devicel3 and of the mixer or converter device |2 produce exceptionallyefficient frequency conversion, especially at ultrahigh frequencies ofthe order of to megacycl'es and higher. It is very simple to adjust thetuned circuits l4 and 29 so that they may be controlled in unison by asingle mechanical control. Although my invention has certain specialadvantages when used at ultra-high frequencies, it may also be used toadvantage at lower frequencies. 'While I have shown and described aparticular embodiment of my invention, it will be obvious to thoseskilled in the art that changes and modifications may be made withoutdeparting from the invention in its broader aspects, and I, therefore,aim in the appended claims to cover all such changes and modificationsas fall within thetrue spirit and scope of my invention What I claim asnew and desire to secure by Letters Patent of the United States is:

1.'In combination, an electron discharge device having a cathode, acontrol electrode and an anode, resonant frequency determining meanscoupled between said anode and control electrode, a load device spaced asubstantial distance from said electron discharge device, a circuitincluding the anode-to-cathode path of said discharge device, said loaddevice, a source of operating potential, and connections between saidload device and said discharge device, said circuit carrying thedischarge current flowing through said discharge device and transferringoscillatory energy therefrom to said load device, said connectionsproviding substantial capacitive reactance at said resonant frequencybetween said cathode and a point on said frequency determining means,and means providing capacity between said cathode and another point onsaid frequency determining means for maintaining the alternatingpotential of said cathode intermediate the alternating potentials ofsaid control electrode and anode, whereby said electron discharge devicemaintains oscillations in said frequency determimng means and saidcircuit transfers such oscillations efficiently to said load device.

2. In combination, a frequency converter having a wave impressed thereonto be converted to another frequency, a discharge device having ananode, a cathode and a control electrode, said converter and said devicebeing mounted on the same conductive chassis and being spaced apart asubstantial distance, resonant frequency determining means connectedbetween said anode and control electrode, a circuit serially includingthe anode-to-cathode path of said device, a connection from said cathodeto said converter, said converter, said chassis and a source ofoperating potential, said circuit carrying the discharge current of saiddevice and transferring oscillatory capacitive reactance therebetweenfor currents of said resonant frequency, said reactance tending tomaintain said cathode at the potential of a point on said frequencydetermining means, and means comprising capacity between said cathodeand another point onsaid frequency determining means for maintainingsaid cathode at an alternating potential intermedidate the potentials ofsaid anode and control electrode, whereby said device producesoscillatory energy and such energy is eificiently transferred tosaidconverter through said circuit. I

3. In combination, a conductive chassis, an electron discharge devicemounted on said chassis and having a cathode, a control electrode and ananode, resonant frequency determining means coupled between said anodeand said control electrode, a point on said means being connected tosaid chassis for currents of said resonant frequency, a load circuitmounted on said chassis and separated from said oscillator by asubstantial distance, a conductor connected from said cathode to saidchassis through said load circuit, said conductor and said chassispresenting substantial capacitive reactance between said cathode andsaid point at said resonant frequency, and a capacitance between saidcathode and another point on said frequency determining means so placedwith respect to said first point as to form with said capacitivereactance a voltage divider arrangedto maintain said cathode at analternating potential intermediate the alternating potentials of saidanode and control electrode, thereby to cause oscillations in saidfrequency determining means and to excite saidconductor for the transferof said oscillations to said load circuit.

' PAUL C. GARDINER.

